Transcript: February 28 - March 5

RACHEL
Welcome to Idaho Skies for the fifth week of February. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
Zubenelgenubi is a star that’s easy to split into two separate stars through binoculars.

PAUL
Astronomers call stars like this double stars.

RACHEL
Binoculars show Zubenelgenubi as two separate stars because the separation between them is wide at 4 arc seconds.

PAUL
Can you describe an arc second?

RACHEL
Sure. An arc second is 1/60th of a degree.

PAUL
So the separation between the two stars making up Zubenelgenubi is 4/60ths of a degree, or 1/15th.

RACHEL
That’s right. And that’s large enough of an angle that some people can split Zubenelgenubi into two stars with just their eyes.

PAUL
The problem is not splitting Zubenelgenubi into two stars, but finding it in the first place.

RACHEL
The reason it can be difficult to find is that it’s located in a rather blank portion of the sky.

PAUL
That’s where the moon comes in handy.

RACHEL
Zubenelgenubi will be the star below the moon on the morning of the 28th.

PAUL
Get your binoculars out and take a peek at Zubenelgenubi and then see if you can split it into two stars without your binoculars.

RACHEL
An even more famous double star is Mizar and Alcor.

PAUL
This pair of stars is located in the bend of the Big Dipper’s handle.

RACHEL
And the timing is perfect because you’ll find Mizar and Alcor in the high north on the 28th.

PAUL
The separation between the brighter Mizar and fainter Alcor is 14 arc seconds.

RACHEL
Or half the apparent diameter of the moon.

PAUL
This means everyone with good vision can resolve Mizar and Alcor as separate stars.

RACHEL
Rumor has it that ancient people used the pair as a vision test.

PAUL
So take a few minutes of your time after midnight of the 28th to test your vision on these two double stars.

RACHEL
The Angry Red Planet...

PAUL
...that’s Mars...

RACHEL
...is below the moon on the morning of the 29th.

PAUL
Do you remember that the moon passed close to Mars back on the 1st?


RACHEL
Back then, Mars was located just above Zubenelgenubi.

PAUL
Now, a month later, Mars has moved 12 degrees further east.

RACHEL
Look in the low south at 5:00 AM for the moon and you’ll see orangish Mars four degrees below the moon.

PAUL
A separation of four degrees means you can see both in a pair of binoculars.

RACHEL
However, you’ll need to place the moon near the very top of the field of view.

PAUL
Earth is approaching closer to Mars.

RACHEL
This means Earth and Mars will be at their closest in May.

PAUL
So soon, good telescopes will begin showing surface features of Mars.

RACHEL
Features like Syrtis Major and Hellas.

PAUL
That’s Idaho Skies for the last week of February. Next week the moon helps locate two planets. 

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel...

PAUL
...and Paul.

RACHEL
Dark skies and bright stars.